Announced through Twitter, Aniplex of America announced that the anime movie Sword Art Online: Ordinal Scale is available for digital platforms. According to the tweet, you can buy/rent the movie on Prime Videos (Amazon), Xbox. iTunes and Vudu. Someone mentioned if this movie is also coming to Playstation and it will be added later. So, if you want to watch this movie in a quick and convenient manner without paying for a physical copy, you can rely on digital. The movie will be available for users who wants to watch it in English Dub or Subbed.
I checked in iTunes and if you are in North America, the movie costs $14.99 if you want to buy it. Renting the movie will be $4.99.